GENETIC-STUDY OF THE PVM82 PLASMID RESPON SIBLE FOR SOME PATHOGENIC TRAITS OF YERSINIA-PSEUDOTUBERCULOSIS

The large pVM82 plasmid isolated from epidemic strains of Yersinia pse udotuberculosis includes the 25MD segment, which encodes a series of p roperties affecting the virulence of the bacterium. Insertion mutants of pVM82 containing transposition-defective Tn2507 with a kanamycin-re sistance marker in different Hind III fragments of the 25MD segment we re obtained. By recombination between two homologous pVM82 containing genetic markers in different parts, deletion derivatives of pVM82 plas mid and insertions of the plasmid segment, carrying kanamycin-resistan ce marker, into a chromosome were obtained. Results were obtained sugg esting the presence in the plasmid 25MD segment of a transposon-libe s tructure capable of migrating from pVM82 plasmid onto a chromosome and from a chromosome and pVM82 onto pRP1.2 plasmid of a broad host range .